Cauliflower is not the easiest to grow. It requires cool temperatures and consistently moist, well-fed soil. Even if you get all of that right, you may need to blanch your plants to get those nice white heads on your cauliflower.
How to Blanch Cauliflower
Some varieties of cauliflower are bred to blanch themselves. If you do not grow one of those varieties, though, blanching is a good idea to ensure that you get a white curd. Otherwise, there’s a chance that it will start to turn green or develop sprouts between the curds.
About a month after you’ve planted your cauliflower seedlings, check your plants to see how the curds are developing. When they are tiny, the outer leaves can protect the curds from the sun. By the time the curd is 2 to 3 inches wide, it’s time for blanching.
At this point, you tie the large outer leaves over the curd. You can use twine or rubber bands. Make sure you don’t tie the leaves too tightly – the curd still needs room to grow! That will also help with air circulation to prevent fungus. Because cauliflower heads grow pretty quickly, you’ll want to check on them regularly.
Generally, cauliflower is ready to harvest 2 to 3 weeks after blanching in the fall. In the spring, your cauliflower should be ready for harvest in less than a week.